Lock washer



FIG. 1 is a top-plan view of a lock washer, showing my new design;

FIG. 2 is a cross-sectional view taken along line 2--2 of FIG. 1;

FIG. 3 is a side-elevational view thereof; and

FIG. 4 is a bottom-plan view thereof. 

The ornamental design for a lock washer, as shown. 